1. Field of the Invention
This invention relates to apparatus and method for dismantling, shearing, and compacting a fuel assembly frame skeleton.
More particularly, the invention relates to apparatus and process for on-site storage and off-site disposal of the fuel assembly frame skeleton. More specifically, the invention is concerned with the compaction of the non-fuel bearing parts.
With this invention, remote dismantling of the fuel assembly frame skeleton is facilitated and the costs are reduced because the volume for eventual storage is reduced while the fuel rods and top nozzle can be removed and saved.
Heretofore, because of a lack of spent fuel reprocessing capability and lack of or insufficiency of Away-From-Reactor (AFR) storage facilities, it is necessary to have extended storage capability at reactor sites. This is presently being accomplished by storage-rack densification and trans-shipment between stations.
2. Description of the Prior Art
Both fuel assembly reconstitution and fuel assembly consolidation result in frame skeletons that must be disposed of.
It is, therefore, an object of this invention to reduce the volume of the skeletons and prepare them for permanent off-site disposal.
Methods and apparatus have been considered by others for the removal and disposal of unwanted materials both in the nuclear and non-nuclear field. Additionally, consideration has been given to the retention and saving of some of the components while at the same time disposing of the unwanted, unneeded, as well as undesired components.
As an example of a method for disposing of nuclear waste, although not particularly pertinent to the present invention, reference is made to U.S. Pat. No. 3,763,770 to Ehrman et al. which proposed a method for shearing spent nuclear fuel bundles into units of predetermined length and provided apparatus for carrying out the aforesaid method. This apparatus generally includes a pair of orthogonally related "gags" to clamp and collapse the bundle or a pair of parallely-acting horizontal gags cooperating with a vertical restraint for compressing predetermined lengths of the fuel bundles. Then a shear blade is used to sever predetermined lengths for dropping through a chute to a dissolution apparatus. The entire fuel bundle is merely collapsed and severed into smaller units for eventual disposal.
Also in the nuclear waste field, but not particularly pertinent to the present invention or the problems involved is the U.S. Pat. No. 4,056,052 to Weil et al., which is concerned with a method for shearing spent nuclear fuel assemblies of the shrouded pin-type wherein a plurality of long metal tubes packed with ceramic fuel are supported in a spaced-apart relationship. Spent fuel nuclear assemblies are first compacted between specially provided gag compactors into short segments so that they are amenable to chemical processing. Compression takes place so as to form the assemblies into specially formed compacts. Shearing then takes place with specially contoured blades which are adapted to mate with the contoured surface of the compacts of the compressed fuel assemblies.
There are other methods and apparatus for disposal of unwanted material, while retaining certain desired materials, and for this purpose reference is made to other patents which have no concept or appreciation of the problems involved with spent nuclear fuel assemblies, so that their solutions are of no help with the problems the present invention desires to overcome.
For example, U.S. Pat. No. 3,180,249 to Patros is concerned with compacting of scrap metal for steel mill consumption. This is a special process uniquely concerned solely with automobile bodies which are to be formed into scrap metal segments for cleaning prior to use in a steel mill. Here, there is no concern with bodies contaminated with nuclear material or nuclear waste material.
U.S. Pat. No. 3,367,019 to Williamson, U.S. Pat. No. 3,320,051 and U.S. Pat. No. 3,606,809 to Chazen are also all concerned with apparatus and methods for compacting and shearing scrap material such as automobile bodies.
However, none of the prior art known to the inventors is concerned with remotely dismantling and compacting an irradiated skeleton for off-site shipment or on-site storage.
It is therefore an object of the present invention to provide equipment which is capable of and usable for remotely dismantling and compacting a fuel assembly frame skeleton.
Another object of the present invention is to reduce the volume of the fuel skeleton.
A further object of the invention is the reduction of the fuel cell skeleton, which consists of everything composing the fuel cell assembly except the top nozzle and fuel rods, by a factor of four.
Yet another object of the invention is to carry out the process of reducing the fuel cell skeleton under water to provide protection against radiation.